Question

The duration of cardiac cycle in a normal man is (a) \(0.8\) seconds (b) 80 seconds (c) 60 seconds (d) 72 seconds

Short answer

The duration of the cardiac cycle in a normal man is \(0.8\) seconds.

Step-by-step solution

Understanding the concept of a cardiac cycle

A cardiac cycle is the period from the start of one heartbeat to the beginning of the next. It includes both the contraction (systole) and relaxation (diastole) phases.

Familiarizing with the normal duration of a cardiac cycle

The length of the cardiac cycle is usually expressed in seconds. A normal cardiac cycle in a healthy human at rest usually takes around \(0.8\) seconds. So, this is the most appropriate answer among the given options.

Key concepts

Systole and Diastole Phases

Understanding the intricacies of the heart's function is crucial to grasping human physiology, particularly the systole and diastole phases that constitute a single heartbeat. During systole, the heart's muscle fibers contract to pump blood out of the heart chambers — the left ventricle sends oxygen-rich blood to the body, while the right ventricle pumps oxygen-depleted blood to the lungs. Contrastingly, diastole is marked by the heart muscle relaxing and the chambers filling with blood, preparing for the next pump.

These phases are critical for maintaining blood circulation throughout the body and ensuring that each organ receives the oxygen and nutrients it needs. It is this rhythmic alternation of contraction and relaxation that sustains life. For students in pursuit of human physiology, visualizing or using diagrams can offer significant aid in comprehending how these phases work in tandem to maintain blood flow.

Heartbeat

The heartbeat is a vital sign that reflects the cyclic pattern of the heart as it contracts and relaxes. In human physiology, this cycle is known as the 'cardiac cycle.' It starts with an electrical signal generated by the sinoatrial node, also known as the heart's natural pacemaker. This signal triggers the contraction of the atria, followed by the ventricles, leading to the systolic phase. The diastolic phase follows as the heart muscle relaxes.

To fully grasp the cardiac cycle, it's beneficial to listen to actual heart sounds with a stethoscope or use interactive tools that simulate the heartbeat. This can assist in identifying the 'lub-dub' sounds associated with the closing of heart valves, which correspond to the systolic and diastolic phases. For accurate measurement of the heartbeat, medical professionals often use electrocardiograms (ECGs), which showcase the electrical activity of the heart in detail.

Human Physiology

Human physiology is the study of how the body's systems and organs interact, function, and respond to various challenges. It encompasses an array of processes, with the cardiac cycle being a prime example of the body's complex internal workings. The duration of the cardiac cycle, which we've established is traditionally around 0.8 seconds in a resting adult, is pertinent to the field as it indicates the heart's efficiency and responsiveness to bodily demands.

In educational settings, utilizing cross-sectional studies and observing variations in cardiac cycle duration among different individuals can provide deeper insights into cardiovascular health. External factors such as exercise, stress, and illness can also influence the cardiac cycle's duration, making human physiology a dynamic and captivating subject. Remember, when examining human physiology, context is key, and understanding how different systems interconnect can unlock a comprehensive view of human health.